Moving the position of the Snyk Delta to execute as the first stage as there seems to be issues with running the under the hood 'snykResolvedDepsJson' task after other gradle tasks have been executed. To be investigated further but this should unblock and PR's hitting the Snyk Delta stage.
* removed `.ci/dev/unit/Jenkinsfile` and
`.ci/dev/integration/Jenkinsfile` - they don't seem to be used anywhere
* switched mandatory tests to linear build - modeled after Corda
Enterprise
* switched nightly regression tests to linear build - modeled after
Corda Enterprise
* Update to Jackson 2.9.8 to address multiple security issues, and update warning note about
updates to clarify that it refers to 2.10+. When the note was added 2.9.7 as the highest
available version in the 2.9.x series.
* Add PR code checks Jenkinsfile
